1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to synchronizing home network devices, and more particularly, to synchronizing contents contained in devices in a Universal Plug and Play (UPnP) network.
2. Description of the Related Art
Universal Plug and Play (UPnP), which is a protocol for sensing and controlling electrical appliances connected to a network, is a home networking standard. A UPnP AV (Audio/Video) architecture was developed for utilizing multimedia content, such as audio/video, etc., on the basis of the UPnP standard.
The UPnP AV architecture consists of a media server, a media renderer, and a control point for controlling the media server and the media renderer. The media server provides multimedia files through a content directory service, and the media renderer reproduces the multimedia files. The control point controls the media server and the media renderer so that they can operate by interacting with each other. The content directory service provides metadata regarding contents used both inside and outside of a home network. The control point acquires information regarding content by means of the content directory service, and sends requests to the media renderer to reproduce the content.
If such a UPnP AV architecture is established, a plurality of media servers can exist in a home network, wherein the media servers can contain different content. In a UPnP AV environment, a user may want to easily synchronize content distributed to different content directory services (CDSs); for example, a user may want to synchronize an MP3 player with a home media center in order to be able to listen to music content stored on the MP3 player through a high-quality home Hi-Fi apparatus.
FIG. 1 is a view for explaining a conventional method of synchronizing content directory service devices providing control directory services.
Referring to FIG. 1, a case is depicted wherein a user wants to synchronize control directory services between a first device CDS#1, and a second device CDS#2, by manipulation of a control point. Synchronizing the control directory services means synchronizing Digital Item Declaration Language Lite (DIDL-Lite) metadata for a plurality of directories that are to be synchronized. For example, if a directory A of the first device CDS #1 is synchronized with a directory B of the second device CDS #2, the control point will receive response messages when the control point browses the two directories A and B.
In order to synchronize two devices providing control directory services, the control point first performs synchronization setup. The synchronization setup refers to a process of providing a synchronization document to the two devices. The synchronization document for synchronizing the two devices providing the control directory services may include information regarding identifiers of devices and directories that are to be synchronized, a synchronization policy, etc.
If the synchronization setup is complete, the control point requests synchronization of the first device CDS #1 on the basis of the synchronization document in which synchronization between the first device CDS#1, and the second device CDS #2, is defined. Accordingly, the first device CDS#1, and the second device CDS #2, exchange information to be updated from their content lists, and then perform synchronization.
In the synchronization process, since a synchronization setup request, a synchronization request, the exchange of update information required for synchronization, etc., can be performed by an action provided by the control directory services, the first and second devices CDS #1 and CDS #2 which provide the control directory services can be relatively easily synchronized.
However, since the control point includes a local reproducer and a storage device, when a user tries to reproduce and store content by using the control point, a problem exists in that the control point and a different device providing a control directory service cannot be synchronized. This is because the control point cannot provide the action for performing synchronization required by a different device when the control point provides no content directory service. For example, a different device cannot browse a list of content included in the control point, and also cannot request update information required to perform synchronization with the control point.